Add the Linux scheduling docs the databento port left behind

[mspinola]

#15 moved the databento provider here; its operational half stayed in cotdata and then went with cotdata's own price docs. So the box that actually runs databento has a wrapper calling cotdata-prices — an entry point that no longer resolves — and nothing in this repo telling it what to call instead.

• docs/examples/linux/run-prices.sh — the replacement to copy onto the box
• docs/LINUX_SCHEDULING.md — crontab, flock, troubleshooting

Two changes from the script it replaces, both about not paying twice

Stage 2 now runs even when Stage 1 fails, and the script drops set -e to allow it. Stage 1 is the only step that costs money, it writes incrementally, and it is resumable — so a network failure partway through still leaves new raw data on disk. Aborting before the free local rebuild would discard something already paid for, and the next run would have to pay again to reach the same place. Stage 1's exit code is captured and returned, so cron still sees a failure and still retries.

The cold-start backfill is documented as a manual step, not the nightly job, with --windowed-n1-stats on it. That flag restricts the second contract's statistics to windows around roll dates — the only place that series is read, so it is accuracy-neutral and it is the largest avoidable download. It buys nothing on a nightly incremental, so it does not belong in the crontab line.

Troubleshooting leads with the failure this move causes

command not found, from a wrapper still calling cotdata-prices.

It also covers the stuck-symbol case worth knowing about: a ledger entry claiming rows whose parquet is missing still carries a current last_date, so every run skips it as "already current". No error, no row, a permanent hole in a paid dataset. --reconcile-databento is the repair, and it fixes both directions.

Verified rather than asserted

• the quoted no databento-capable symbols message matches the provider's actual string
• the eight databento: null markets are the eight named (CC, CT, DX, KC, LBR, OJ, SB, WBS)
• the rc-propagation shape was exercised with a stub: both stages run, exit code 7 survives

ruff clean; 200 passed, 12 skipped (unchanged — docs only).

Still needs a human

I can't reach the server, so the wrapper on it is unchanged. Copy this file over, fill in the three markers, and update the crontab path.

---

Generated by Claude Code